Cold War: Igor Gouzenko, a Soviet Union embassy clerk, defects to Canada, exposing Soviet espionage in North America, signalling the beginning of the Cold War.

The Cold War was a period of international geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc. It began in the aftermath of the Second World War and ended with the dissolution of the Soviet Union in 1991. The term cold war is used because there was no direct fighting between the two superpowers, though each supported opposing sides in regional conflicts known as proxy wars. In addition to the struggle for ideological and economic influence and an arms race in both conventional and nuclear weapons, the Cold War was expressed through technological rivalries such as the Space Race, espionage, propaganda campaigns, embargoes, and sports diplomacy.